A Large Iridescent Ammonite, Canada

From the Upper Cretaceous Bearpaw formation (75-72 million years ago). Gem ammonite with hints of blues and purples on both sides and also has areas with reds, oranges, golds, and greens. A highly sought after combination of colors considering purple and blue are the most uncommon iridescent colors of ammolite.

Note: The opal-like iridescence of these ammonites from Alberta, Canada has been termed "ammolite," and since 1981 has had the status of a gemstone. The shimmering, metallic colours were caused by the combination of millions of years of compression and the mineralization of iron, copper, and silica which precipitated from volcanic ash. The opalescent layers of colour are particularly prized in the Chinese philosophical system of Feng-Shui. The ammonites are a group of molluscs that lived in the seas from the mid-Devonian (approximately 400 million years ago) to the end of the Cretaceous (65 million years ago). The sequence of events that famously killed off the dinosaurs also drove the ammonites to extinction.